Control of <i>Heracleum mantegazzianum</i> with pyrolysis liquid products

Abstract Heracleum mantegazzianum is an invasive environmental weed that is widely distributed in Europe and whose distribution is continually expanding. Novel management methods are required to address its impacts and spread. We studied the use of pyrolysis liquids (PL) as a component of biodegradable mulch and as biobased herbicide to control H. mantegazzianum . A five‐year field experiment was conducted to compare pyrolysis liquid peat mulch (PLM) with plastic PE–mulch, biobased Ökolys® mulch and glyphosate. Application of PL biobased herbicide after stem cutting was studied in a one‐year field experiment. We established that PLM does not control the growth or reproduction of mature H. mantegazzianum effectively in contrast with the other mulching materials and glyphosate. The coverage of H. mantegazzianum differed only in 1 year between application of PLMs and the control. The number of flower stems increased in PLM treatments and in the control, indicating that PLM failed to control reproduction and spread of H. mantegazzianum . PL treatment of cut H. mantegazzianum stems was more effective than application of acetic acid alone. The results suggest that biobased control methods do not provide as effective control of H. mantegazzianum as widely used current methods (plastic mulches and glyphosate). If biobased methods are to be more widely used for controlling H. mantegazzianum , lower control efficacy must be accepted, and they should be used in an integrated approach with other methods.